


Volume Control

by MeGaLoTrash



Category: Undertale (Video Game)
Genre: Don't get caught, Ecto-Penis (Undertale), Ecto-Tongue (Undertale), Ectobiology, Explicit Language, Explicit Sexual Content, Fluff and Smut, M/M, Mentioned Alphyne - Freeform, Post-Undertale Pacifist Route, Sharing a House, classic fontcest
Language: English
Status: Completed
Published: 2017-08-01
Updated: 2017-08-01
Packaged: 2018-12-09 19:52:10
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,640
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11675931
Author URL: https://archiveofourown.org/users/MeGaLoTrash/pseuds/MeGaLoTrash
Summary: The Skelebros share a house with everyone on the surface and try to keep their relationship a secret... it doesn't end well.





	Volume Control

**Author's Note:**

> A prompt from @brotherly-slime-emission on tumblr, thanks for letting me run away with it a little! <3

“-but pap, you’re not exactly...quiet”

“THE GREAT PAPYRUS CAN BE QUIET! I CAN BE AS QUIET AS A MOUSE, SILENT AS A SNAKE! NYEH HEH HEH!

“kinda proving my point there bro”

“I DIDN'T KNOW YOU MEANT NOW!” 

Sans shook his head and laughed, leaning back on the headboard of Papyrus’s bed. They were currently enjoying a rare five minutes of the house being empty, and Papyrus had decided to bring up some pressing issues. Sans thought his brother was cool, really caring and considerate. So considerate in fact that he’d insisted on moving in with all their friends to help them adjust to life on the surface. It was great. Sans loved having everyone around, pulling pranks on people from the comfort of his own home. Perfect. 

The only problem was, having so many people around drastically reduced any private time. When it was just Papyrus and him in that detached house in Snowdin, they enjoyed a lot of alone time. Just before they had moved to the surface, that time together had turned into something more than brotherly. Sans still wasn’t sure who was the instigator, they had been skirting around their mutual feelings for a few years, but Papyrus had been the one to invite him into his bed. While this type of relationship was not unheard of between monster kind, _weren’t the dog guards technically siblings now their parents were the same entity?_ , it wasn't something you shouted about. 

Sans used to not care what people would think. In his mind he and his brother were meant to be together, they were the last of their kind. Plus Papyrus was the best, Sans could feel how their souls beat as one, and he’d do anything to make him smile. However being open about their relationship while it was still in early stages ran too high a risk. Sans could cope with the backlash but he couldn’t bear to see Papyrus get hurt. It wasn’t a perfect arrangement, but Sans wanted to make sure Papyrus was well prepared for the fallout, and that took time. 

Recently, that time felt like it was running low. They shared a room in the new house, even if their standards over living conditions clashed, they strived to make it work. Sneaking into the same bed every night wasn't the issue. Papyrus was, for lack of better description, very vocal in the bedroom. Just like the his full on personality, that level of energy and enthusiasm translated into Papyrus making a lot sinful noises when they were together. It wasn’t that Sans minded at all, he drank up every whimper, moan, and cry of pleasure that Papyrus gave him, thrilled he was the one causing them. It fine when they lived alone…. but not with half a dozen other people and thin walls.

Having sex in their new home was out of the question but...

Looking at Papyrus’s face, so full of love and only inches away from his own. Sans was finding it hard to say no. 

“ok papy, we can try. but we need to start slow... just follow my lead ok?” Sans offered, unable to hold back from placing a chaste kiss against his brother’s teeth. Papyrus pulled him forward and into his lap, planting kisses all over his skull giggling happily. 

“WOWIE! SURE THING SANS! THE GREAT PAPYRUS WILL ACCEPT YOUR CHALLENGE! IT'S JUST LIKE STARTING DATING YOU AGAIN ONLY NOW I HAVE EXPERIENCE!! NYEH HEH HEH!” 

Papyrus tilted Sans’s chin towards him before he had time to protest, a glowing orange tongue pressing at his teeth asking for entrance. Sans felt his control slip slightly and his own tongue forming in response. He parted his mouth slightly, letting the pleased moan Papyrus let out be swallowed in against him. _fuck, i’ve missed this_. Sans let his eyes slip closed when he felt rough phalanges graze the back of his skull. He felt Papyrus unconsciously grind his pelvis up into him lightly. Even though Sans knew it wasn’t a good idea, he could feel his magic responding to finally feeling his lover’s touch. 

_Click_

The sound of the door opening and a few voices filtering upstairs as their friends came back from food shopping. Papyrus jumped at the sound, causing Sans to fall back on the bed with his legs still wrapped around him. His brother squeaked at somehow making the situation look worse before Sans untangled himself and pulled Papyrus down next to him. If anyone decided to come into their room now it would look like they were just taking a nap together. Sans waited to hear if their were any footsteps coming up the stairs before turning to face Papyrus.

“lets... try again tonight, when there’s less of a risk of people moving about” Sans whispered breathlessly, already worked up from that kiss after a few weeks of abstaining from contact. Papyrus nodded and pressed their temples together with a sigh, not trusting himself to make a sound without it being laced with lust. Sans could hear the human asking Toriel about their whereabouts. He saw Papyrus quickly cover the orange glow in his lap with the sheets, his demeanour changing as if nothing was wrong. 

Papyrus was really trying, maybe this wouldn’t be so bad after all.

**********************************************************************************************************

It may not have been ideal but Sans had to admit, having the chance to do anything after a dry spell felt amazing. 

They were a mess of limbs, Sans had one hand pumping Papyrus's cock and the other sealed around his mouth. Sans had checked and double checked the lock on their door before heading to bed but he couldn’t help being on high alert for any signs of movement around the house. Hearing Papyrus struggle to keep quiet even with his hand clasped around his mouth was conflicting him greatly. On the one hand, his conscience was screaming at him for even trying something so risky. On the other… he wanted to climb on top of the swelling length and fuck himself senseless. While he flipped between his preferred genitals depending on what he and Papyrus had planned, he couldn't help his magic forming a dripping cunt at the sight of his brother bucking into his hand.

Even though Sans loved his brother’s pretty pussy, Papyrus tended to reach higher octaves if he was on the bottom. Plus there was something about the way Papyrus rutted against him that made the lack of stimulation on his part a lot more bearable. Sans could see the way Papyrus was looking at him even in the darkness of their bedroom. His eyes were lidded and glowing, and Sans could hear the thrumming of Papyrus’s soul against his sternum. His expression held a rare flicker of aggression, as if he was barely holding back from pinning Sans into the mattress and thrusting his cock where it belonged. Sans wondered if his brother could smell his arousal through his shorts. 

Papyrus’s muffled whines were slowly climbing in volume and Sans became very aware how quiet the house was. _Shit_. Sans was glad they had experimented first, he would have to plan some background noise if they ever worked up to fucking. With the way Papyrus was looking at him, he knew his resolve would eventually crumble. Sans slowed his hand slightly, allowing Papyrus enough time to calm down before removing the hand over his brothers mouth. 

“Sans I-I’m-” Papyrus spoke in a strained whisper, the need for release painted all over his features. Any thoughts Sans had of stopping dissolved quickly as his mind scrambled to think of a solution.

“bite the pillow pap, if you get any louder we’ll have to stop” Sans whispered, moving down his brother’s body after he nodded in agreement. 

Sans took Papyrus into his mouth slowly, knowing that any sudden movement would have him crying out. Sans knew from past experience he could bring Papyrus to a more controlled climax this way. The added wetness and licks of his tongue would push his brother over without the frantic motions of his hand alone. 

Sans ran his free hand over his brother’s ilium lightly, the practised touch over the smooth bone making Papyrus arch into his mouth further. Sans knew he was close. In any other circumstances he would have teased him more so he could enjoy how debauched he looked underneath him. Papyrus was biting down hard on the pillow, one hand keeping the material in his mouth and the other fisting his bedsheets as he struggled to hold on. Sans took him further into his conjured throat, flexing the ecto-flesh to tighten around him. Their eyes locked for a moment and Sans issued a silent plea for Papyrus to keep quiet.

The slowness of his movements and the pillow eating all of his brother's cries meant Sans was caught a little of guard when he felt the first spurt in his mouth. Papyrus was biting down on the pillow hard, eye sockets screwed shut as he moved his hand towards Sans’s skull. Papyrus held him still as he bucked his hips upward, slamming deep as he came. Sans could feel his conjured throat filling. Some of the release dripped through the back of the formed organ and onto his soul. It sent unexpected pleasure around his small frame as his sensitive core was touched. He whimpered around the twitching cock in his mouth, thankful for it acting as a gag.

Within seconds of him finishing Papyrus was on him, flipping their position and pinning Sans on the bed. He kissed away all his pent up moans, groaning at tasting himself on their tongues. Papyrus had managed to maneuver Sans’s legs open and he wasted no time in shoving his hand between them and into his shorts. Sans whimpered into the kiss at the contact. He had resigned himself to just getting Papyrus off tonight but it seemed like his brother had other ideas. Soon long phalanges were teasing his folds, playing with his slick entrance before plunging inside.

Papyrus all but growled into their kiss when he felt how wet he was already. Sans knew he should be being more careful but the rough handling he was getting was clouding his vision. It seemed the weeks of pent up sexual frustration had really brought out a primal side of Papyrus. The way he was looming over Sans really exaggerated their height difference, the look on his face as he scissored his fingers was predatory. _Hungry_. Sans had to bite his tongue as they separated, Papyrus’s thumb coming up to circle his clit almost made him cry out. 

“p-pap! not so fast!” Sans practically begged, his writhing up into his brother’s touch doing little to back his words up. Papyrus brought his free hand up to stroke the side of cheek in an affectionate gesture, before clamping his hand over Sans’s mouth when he pressed his fingers in deep. 

“I Can Feel You're Close Brother- I'm Sure You Can Keep As Quiet As I Did- Cum For Me” 

Papyrus didn’t give him chance to answer as he started pistoning his fingers faster, hitting that sweet spot inside Sans almost every time. Sans could feel his vision get hazy, the background fading and his vision flooded with the sinful image of Papyrus licking his teeth. Nearing his climax Sans bit down on his tongue harder, the spike of pain doing the opposite of what he wanted. He felt the hand on his mouth clamp down as his inner walls tightened. Sans knew he should be being more careful, but with the lack of contact and the adrenaline coursing through him he came hard. 

Sans arched his spine up into his brother as he reached his peak, flushing further as he saw the glint of satisfaction in Papyrus’s eyes. It was so good, he felt amazing…. but if Papyrus’s expression was anything to go by this had just made him hungry for more. Sans knew his brother well enough to tell when Papyrus wanted something, it was an interesting feeling to have that attention on him. 

Papyrus withdrew his fingers as Sans came down from his high, making a show of cleaning them with his tongue. _where the fuck had he learnt to do that?!_. Sans would be lying if he said he wasn't craving more already. Papyrus removed the hand over his mouth and leant down to kiss him again lazily, the energy between them still sending shivers through them both. Sans felt his soul thrum heavily in his chest, calling out to his brother, needing them to connect further.

With a soft sigh Papyrus pulled back first, listening out for any disturbance in the house. When he was satisfied he moved to the side of Sans’s frame and pulled him into a spooning position. Sans was still panting quietly, trying to calm himself enough as logic came crashing back. It didn’t help that he could feel Papyrus’s half hard length pressing into him, having never fully dispelled. 

Sans stared at his empty mattress trying to gather the strength to move. All he wanted to do was stay all night in his brother's embrace but he knew they were already pushing the boundaries of getting caught. He could feel the magical residue from their coupling start to disappear as reality came crashing through. Reluctantly he untangled himself from Papyrus, against the other’s sleepy murmurs of him to stay. He climbed into the bed opposite, thankful their mattresses were close enough that he could reach out and touch Papyrus’s hand. They were lucky no one seemed to have stirred in the full house. 

Sans had a feeling their luck wouldn't last. 

*************************************************************************************************************

The sexual tension between them came to a head few days later when they were cleaning the dishes. Sans was on a stool as he couldn't quite reach the top shelf, and Papyrus kept brushing past him to put things away. His pelvis was rocking into him just a little too hard for it to be an accident. Sans was trying his hardest not to blush as Papyrus pretended not to notice anything was wrong. Undyne and Alphys were still sat at the kitchen counter discussing a new anime they were watching and Toriel and the Human were sat a few feet away in the living room. Papyrus was playing a dangerous game and Sans felt like his resolve was crumbling. He had to figure out a way for them to slip away from everyone else before things escalated. 

A spark of inspiration hit him, they still had laundry to do. It was meant to have been done this morning but Papyrus had distracted him with a heavy makeout session against their bedroom door. He knew the washing baskets were still in the laundry, if he could get Papyrus to help him then when the sheets were done they would have an excuse to sneak into their room. His mind made up, Sans turned to get off the stool only to come face to face with Papyrus. It seemed his brother was more affected that he’d been letting on. His face was showing signs of that predatory look and Sans noticed the faint glow of his already formed tongue. They needed to get out of there. Now. 

“p-pap, wanna help me with that laundry?” Sans raised his voice slightly, trying to keep it steady. He figured if he could get people to hear their conversation, they wouldn’t come looking for them once they disappeared. 

“Sure Thing, Brother” Papyrus probably didn’t mean for that to come off as suggestive as it did, but Sans shivered all the same. He quickly grabbed his brother’s hand, jumping down from the stool and practically dragged him out the kitchen towards the basement. Just a couple of feet more and he could chastise Papyrus’s reckless behaviour.

“Doing the washing this late dears?” Toriel’s concerned voice startled Sans from his thoughts. The basement door was between the open kitchen and living room and they had drawn attention with the speed of the escape. Toriel was sat in her chair helping frisk with his homework and looked concerned over their odd behaviour. _nothing gets past her_ Sans thought, frantically trying to come up with an excuse to get them out of there. Fate was cruel in that his usual quick wit had flown out the window in favor of blind panic.

“YES YOUR MAJESTY, NO NEED TO WORRY! THE GREAT PAPYRUS IS JUST HELPING HIS LAZY BONES BROTHER WITH HIS FORGOTTEN CHORES!” Papyrus chimed in with his usual bravado. Sans was taken aback at how normal Papyrus sounded, but the fact his brother was still facing away from everyone probably made hiding his arousal a lot easier behind volume. 

“Jeez sans you don't half rely on Papyrus! Does he tuck your punk ass in bed at night too?” Undyne teased from her position in the kitchen, her brow arching mockingly at the smaller skeleton. Things had always been a little competitive between them since Papyrus and her became friends.

“heh, what can i say. stops me from feeling bonley” Sans found himself unable to resist a bad joke opportunity. He hoped the familiarity was enough to quell any suspicions over their behaviour. Undyne groaned and Toriel laughed into her hand at the terrible joke before waving them away and turning back to Frisk. It was a close call, _too close_. 

Sans grinned sheepishly and followed Papyrus’s lead into the basement, shutting the door behind them firmly. A strange silence fell between them as they descended the stairs, Papyrus not looking back at him when they reached the bottom as he started loading up the beat-up machine. Sans felt a little put out, he had expected Papyrus to at least acknowledge what happened in the kitchen, but he was content to help him load the machine. He stripped off his shirt and hoodie absent mindedly, knowing they desperately needed a wash as he pouted. They could talk properly once they were upstairs. Seeing the machine full and Papyrus putting in the detergent he adjusted the dials and pressed the power.

 _Click_.

As soon as the machine started whirring Papyrus was on him, pushing him against the cold wall of the basement and moving a hand over his exposed ribcage. All Sans could do was splutter in shock as he was roughly handled by his usually gentle lover. _that explained the silence_. Papyrus had attached his mouth to his cervical vertebrae and bit down lightly and he ground his clothed pelvis against him. The material of his brother’s shorts did little to hide the throbbing arousal rutting into him. Sans heard Papyrus moan at the feeling of his cock getting some much needed friction and he pushed at him away slightly in a panic. 

“pap!- we can't here what if someone comes in” Sans scolded him, worry plastered all over his face. Papyrus however, looked like a cat who got the cream. He leaned back into Sans, his fingers resuming their exploration as he explained his plan. 

“No Brother, Here Is Exactly The Right Place- This Old Thing Could Drown Anything Out” Papyrus wrapped a hand around Sans’s spine, knowing the right points to press to make him whimper “I Need You. Now.”

As if to prove his point the washer clattered and banged as it went through the spin cycle. Sans could hardly think with how worked up he was and Papyrus’s plan was sounding more appealing by the second. Papyrus’s hands strayed into his shorts and Sans couldn't hide that his magic had already formed an entrance. Papyrus didn’t press further, he kept his hand just above where Sans ached for him to touch. His brother had pulled away from him slightly, reluctant to go any further without consent, even if he was panting with desire. The final decision came down to Sans. _fuck_

“we have to be quiet, and quick- and don’t worry about prepping me i’m so fucking wet papy ah-” Sans was cut off by Papyrus roughly pulling his shorts down and pushing him onto the cold floor.Before Sans had chance to complain about the cold on his bare bones Papyrus was ontop of him, the heat coming off him was more than enough to make him forget. Papyrus pried his legs apart, his eyes fixed on the magic in his pelvic inlet. 

“You’re So Beautiful Sans, I Can’t Wait Anymore-” Papyrus fumbled with the front of his shorts pulling out his cock, shivering at the light touches. _had he got...bigger?!_. Sans gulped at the sight of his brothers imposing member as he kneeled between his legs and lined up to his entrance.

Sans choked on a moan as Papyrus started to push into him. He could feel the magic of his entrance stretch thin to accommodate his impressive length. The faint blue glow of his magic showed the the darker orange through it as Papyrus hilted to his base. Sans could see his brother’s cock fully in his pelvic inlet from this angle. The sight along with the overwhelming feeling of fullness was enough to bring him close to cumming already. He had to place his hand in his mouth and bite down to stop crying out. 

Papyrus stilled inside him when he was fully inside. The effort of keeping quiet and not ploughing into the writhing body below him was written all over his face. They made eye contact and Sans could tell he was waiting for permission to continue. He found himself unable to say no to his brother any longer, and gave him an enthusiastic nod. 

Papyrus was relentless in building up a pace, quickly pulling almost all the way out before snapping his hips back. He pulled up Sans’s legs to wrap around him causing the smaller skeleton to have to arch his back off the floor. Papyrus was hitting deeper on each pass, his eyes screwed shut in ecstasy after holding back for so long.

“ah slow down papy i can’t ah-” Sans scrambled to get out, all too aware every word sounded dangerously like a moan. He tried to shut everything out for a second and focus on the noises in the rest of the house. Thankfully there was nothing out of the ordinary yet, but with the way Papyrus was going he knew that wouldn’t last. 

“S-Sans! You Feel SO Good- I’ve M-Missed This So Much Ah!” Papyrus cried out, the control over his volume crumbling due to the tight heat clamping down on him. His eyes snapped open and Sans was treated to a faint orange glow and an expression of pure lust. Instead of slowing down his thrusts became more aggressive as he gave into his baser instincts and drilled into him hard enough for Sans to see Stars. They both knew it was wrong, that they could get caught at any moment, _but it felt so fucking good_. 

“hnnng papy! you’re amazing but- ahh slow down- i’m so close” Sans hissed through clenched teeth. He could barely contain his moans now he had moved his hand away to grasp at the cold floor in vain. Papyrus gripped tighter on his hip with one hand, moving the other to play with the bundle of nerves above his entrance. Sans arched his back up further than he thought possible into him, giving Papyrus a show of a trembling rib cage and a dripping soul. 

“SANS! Ah I Can’t Hold Back, I’M GONNA AHHH-” Papyrus’s thrusts became jerky as he neared his climax. Sans felt him swell inside his already stretched magic, he couldn’t stop crying out even if he wanted too. 

Sans vaguely registered more banging noises over the washer and panicked, willing his magic to dissipate. In his aroused state he couldn’t will it completely away, but in an effort to make it disappear he ended up gripping Papyrus tighter as his inner walls tried to shrink. The reaction from his brother was instant, he hilted himself with a shout as his cock breached the top of the conjured magic. Sans felt the first spurt of hot cum hit his ribcage as the door opened to reveal some very concerned faces. 

“ahhhh no fuuuckkk-” It was too late. Sans couldn't contain his cry as he toppled over from feeling his brothers cum paint the inside of ribcage. Even if he was looking at them upside down from his arched up position he could clearly see the shock on their features. 

There he was, practically naked, trembling with aftershocks and completely covered with Papyrus’s seed. There was no hiding, no pretending and no way to explain it as a misunderstanding to their unwilling audience. With his magic currently occupied in milking the last of Papyrus’s Climax, he couldn’t teleport away either. Not that he would ever leave Papyrus alone like this. No, it was time to face the music. 

“O-OH DEAR THIS IS MOST UNBECOMING OF A LOYAL SUBJECT, FORGIVE ME YOUR HIGHNESS” Papyrus had blurted out upon seeing toriel, somehow making it ten times worse.

No one had spoken yet, trying to see the silver lining in the situation Sans was glad the kid was nowhere to be seen. He didn't need scaring a minor for life weighing on his conscious. Papyrus had the sense to grab at his discarded shorts and hide where they were joined, but it was too little too late. What had been seen couldn’t be unseen. 

“I never pictured Sans as a uke” Alphys spoke first from behind her claws, a red blush spread all over her face. 

“OH MY GOD ALPHYS! WE NEED TO LEAVE, I NEED TO... POKE OUT MY OTHER EYE OR SOMETHING!” Undyne yelled before leaving, dragging the flustered lizard monster with her. 

Sans could feel Papyrus recoil at his best friends tone, but he knew the former head of the royal guard would come around. Especially if her girlfriend had any say in it, Sans suddenly felt very thankful for the scientist's penchant for _interesting_ fan fiction. With that pair gone, it just left them and Toriel, who looked like she was wrestling with some conflicted feelings. 

“I should probably have a serious talk with you both. But maybe it’s best when you’re in a more decent state” The former queen offered with a small smile before shutting the door behind her. 

The washing machine came to a stop with an obnoxious beep. Something about the way it cut through their silence made Sans start laughing. Papyrus joined him and ended up collapsing on top of him as laugher racked his frame. At some point Sans felt tears falling on his cheeks and he held Papyrus as he processed some emotions. 

Their reveal could have gone so much better but, their friends reactions could have been so much worse. Yeah it was a lot for anyone to process but there had been no act of aggression towards either of them. Sans knew they were in the shit but some sliver of relief was washing over him.

“Do You Think The Queen Is Going To Dismiss Us From Her Court?” Papyrus asked through sniffles when he'd finally calmed down.

“what? no pap, she probably just wants to lecture us a bit about appropriate locations. we kinda deserve it _tibia_ honest”

“SANS!” 

“come to think of it, they've all probably never seen ecto-biology. Must have been pretty spooky-”

“-I Swear To God Sans, If I Didn't Love You So Much I’d Ah-” Papyrus was cut off by the smaller skeleton under him dragging him into a kiss. It didn't matter how many times he said it, Sans felt his soul flutter when Papyrus said he loved him. Everything else could wait, his brother made it all worthwhile.


End file.
